The present invention relates to improvements in solids handling for effluent streams containing solids. The typical effluent stream for which the present invention is suitable is the discharge from a kitchen, particularly a restaurant kitchen. Grease traps and oil/grease separators for removal of the oil/grease components from such effluents are known. For example, the Lowe Engineering Company of Lincoln Park, N.J. makes products of this type, as shown in U.S. Pat. Nos. 4,051,024; 4,268,369 and 5,030,357. In addition, Thermaco, Inc. of Asheboro, N.C., manufactures and sells oil/grease removal apparatus under the trademark BIG DIPPER. Exemplary of the patents owned by Thermaco are U.S. Pat. No. 4,235,726 to Shimko, U.S. Pat. No. 5,133,881 to Miller et al., and U.S. Pat. No. 5,360,555 to Batten. The disclosures of these three patents are hereby incorporated by reference. The oil/grease separation devices marketed by Thermaco use various methods for the separation and removal of oil and grease from kitchen effluents, including the gravitational separation techniques and oil-skimming methods shown in the above patents.
Typically, oil/grease separators have infeed units including a straining basket into which the solids are directed and trapped to remove them from the flow so they do not interfere with the oil/grease removal process or with subsequent reprocessing of the removed oil/grease. It is up to a restaurant employee to periodically open the unit and remove the strainer basket and dump its contents. These strainers are objectionable to handle because the solids may have strong odors and liquids may drip out of the basket. Since this is an unpleasant chore, sometimes it""s not done. If the strainer basket fills and is not emptied, the grease/oil separator unit may fail and cause the associated plumbing systems to backup.
Clearline Systems, Inc. of Asheboro, N.C. has addressed these problems with strainer baskets as shown in U.S. Pat. No. 5,360,555 to the present applicant by providing a grinder/pump to periodically extract accumulated solids from an oil/grease separator device. The disclosure of this patent is hereby incorporated by reference. While this grinder/pump has proved effective to periodically remove separated and accumulated solids without the problems associated with strainer baskets, such grinder/pumps have some limitations. Grinder/pumps require electric power and periodic maintenance or replacement, and their moving parts may become jammed by certain kitchen solids such as bones, silverware, or rubber gloves. If undetected, lodged solids can cause grinder/pump motors to overheat and become damaged. A safety hazard exists when persons insert their hands into the inlets of such grinder/pumps to remove lodged solids without taking proper safety precautions. Such grinder/pumps often must be removed and disassembled for servicing, typically by a manufacturer""s technician, hired plumber or electrician.
Accordingly, there is a need in the art for an improvement in devices of this nature to eliminate the problems caused by the presence of strainer baskets and the limitations of grinder/pumps or other similar mechanical pumps.
Eductors (also known as xe2x80x9cinjectorsxe2x80x9d, xe2x80x9cjet pumpsxe2x80x9d, or xe2x80x9cejectorsxe2x80x9d) are known and operate by taking advantage of the so-called xe2x80x9cventuri effectxe2x80x9d wherein introduction of a pressurized motive fluid into a cavity creates a suction in the cavity. This suction in turn draws another fluid or a mixture of another fluid and suspended solids into and through the cavity together with the motive fluid. Eductors are relatively simple and inexpensive compared to mechanical pumps. Eductors have no moving parts to wear or become damaged from use, and are therefore extremely durable in operation. In addition, eductors can be easily sized to suit a wide range of pumping demands.
Such eductors have been applied to address a number of needs. For example, U.S. Pat. No. 5,951,878 to Astrom discloses the use of eductors to clean filtrate from a disk filter apparatus. Similarly, U.S. Patent No. 6,083,384 to Al-Ali discloses the use of eductors to retrieve spilled oil. However, eductors have not been used heretofore to address the need for an improved method for removing solids from an oil/grease separation device.
The present invention fulfills this need in the art by providing an oil/grease separation apparatus including an eductor system for extraction of accumulated solids. In a typical installation, the oil/grease separator includes a chamber having an inlet section for receiving a liquid flow containing water, oil/grease and gross solids, a downstream section for separating the oil or grease from the effluent, and an outlet section for discharge of the residual water through an outlet. The inlet section is provided with a water jet eductor having an extraction port in the lower portion of the inlet section. Gross solids entering the chamber settle in the inlet section where they are periodically removed by actuating the water jet eductor. The water jet eductor is actuated by opening a water supply valve to provide a flow of pressurized water to the eductor through a water supply line. The suction created by the water jet eductor extracts the accumulated solids from the inlet section through the extraction port.
Preferably, the inlet section has a bottom that slopes downwardly toward the extraction port of the water jet eductor to direct accumulated solids toward the extraction port. The apparatus may also include a timer which automatically opens the water supply valve to the eductor for a preset period at a preset time. Alternatively, the water supply valve may be opened by a weight-controlled switch in the inlet section when a preset weight of solids has been collected in the inlet section and closed when the solids have been depleted from the inlet section. The apparatus may also include a grease trap connected to receive the residual water exiting the chamber through the outlet and piping from the water jet eductor that bypasses the grease trap.
Preferably, the jet eductor includes an eductor pipe with a first end in communication with the solids extraction port in a lower portion of the inlet section. The second end of the eductor pipe is connected to the outlet section of the chamber. A jet nozzle is provided in the inlet section of the oil/grease separation apparatus and is positioned to direct a jet of water into the first end of the eductor pipe in the inlet section. This jet of water creates a suction in the eductor pipe which causes a mixture of water and solids accumulated in the inlet section to be extracted from the inlet section through the eductor pipe.
Alternatively, the jet eductor may include an eductor housing in the inlet section of the chamber having a first opening forming a water injection port, a second opening forming a solids intake port, and a third opening in communication with the solids extraction port. A jet nozzle located inside the housing is connected to the water injection port to receive a supply of pressurized water through a supply line and to direct a jet of water through the discharge port. A discharge pipe connects the third opening in the eductor housing to the outlet section of the chamber. The jet of water creates a suction in the housing and discharge pipe, thereby causing the mixture of water and solids accumulated in the inlet section to be extracted from the inlet section through the discharge pipe. In a preferred arrangement, the eductor housing and discharge pipe are located internal to the chamber. Alternatively, the eductor housing and discharge pipe may be external to the chamber. In this alternative installation, the solids intake port in the housing is connected to a penetration in an outer wall of the chamber in a lower portion of the inlet section.
In a typical installation, the oil/grease separation apparatus includes a chamber for receiving a liquid flow containing water, oil/grease and gross solids. The chamber has an inlet section, a downstream section and an outlet in an outlet section. The inlet section is separated from the downstream section by a weir which includes a first wall extending upwardly from the bottom of the chamber to a top above the outlet and a second wall extending downwardly from a height above the liquid level to a submerged level. The weir creates a higher static water level to be maintained in the inlet section than in the downstream section, and facilitates one-way passage of oil/grease from the inlet section to the downstream section. A water jet eductor is provided which has an extraction port in a lower portion of the inlet section for removal of accumulated solids. The inlet section includes an inlet port, a strainer separating the inlet port and the top of the first wall to inhibit the passage of solids to the downstream section, and a bottom which slopes downwardly toward the solids extraction port. An oil/grease separator is located in the downstream section for removing oil/grease from water held in the downstream section. Gross solids entering the chamber settle in the inlet section for periodic removal with some water by the water jet eductor. Oil/grease and water entering the chamber pass to the downstream section where the oil/grease is removed from the water, and the residual water exits the chamber through the outlet section.
The invention also provides an oil/grease separation method that includes the efficient removal of accumulated gross solids. The method includes introducing a liquid flow containing water, oil/grease and gross solids into a chamber having an inlet section, a downstream section and an outlet in an outlet section. The gross solids entering the inlet section are permitted to settle in the inlet section where they are periodically removed with some water by actuating a water jet eductor. Oil/grease and water are permitted to pass from the inlet section to a downstream section where the oil/grease is removed from the water. Finally, the residual water is permitted to exit the chamber through the outlet.
Preferably, permitting oil/grease and water to pass from the inlet section to the downstream section includes passing the oil/grease and water over a weir that maintains a higher static water level in the inlet section than the downstream section. The method also preferably includes straining gross solids from the liquid flow by a strainer in the inlet section to prevent passage of solids to the downstream section. Desirably, the eductor is sized so that the periodic removal of solids creates a reverse flow of water through the strainer to backwash the strainer. The periodic removal of solids may take place for preset periods at a preset times. For example, this may take place for thirty seconds every thirty minutes. Alternatively, the periodic removal of solids may take place when a preset weight of solids has been collected in the inlet section and end when the solids have been depleted from the inlet section. In a typical installation, the method may include directing the residual water exiting the chamber through the outlet section to a grease trap and directing the solids and water removed from the inlet section during the periodic removal step to bypass the grease trap.
The invention may also include a focus plate to concentrate the oil/grease atop the water and a removal means to remove the concentrated oil/grease. The focusing plate may have a ridge aligned with a line between a receiving end and an exit end of the chamber.